Portable scales using strain gauge load cells are common in the prior art. A typical device of the prior art is shown in U.S. Pat. No. 4,714,121. These devices are adapted to support the wheels of a vehicle. The downward weight of the vehicle on the scale and the load cells thereof is transmitted electronically to a visible data readout system whereby the weight of the vehicle can be ascertained.
The load cells of such portable scales utilize conventional strain gauges whereupon the deflection of the load cells is measured by the strain gauges and is transmitted to the readout apparatus which assimilates the collective readings from the individual portable scales located under the various wheels of the vehicle.
The load cells of the prior art are normally comprised of an elongated bar. U.S. Pat. No. 4,775,018 shows such a bar having an elongated slot therein. When weight deflects the bar and compresses the slot, strain gauge therein measure the deflection of the bar and this data is transmitted to the readout apparatus.
Other load cells of the prior art utilize an elongated bar which is supported on one end and which has the other end suspended in cantilever fashion. A strain gauge is placed within a cavity in the cantilevered end of the bar, and the strain gauge measures deflection of the cantilever end of the bar in conventional fashion. Load cells of this type are commonly used in pairs with the bars being positioned in alignment, and the cantilevered ends thereof extend in opposite directions from the inner ends which support the bar on a supporting surface.
Among the shortcomings of the prior art devices is that they do not possess the strength which is often required to weigh large and heavy vehicles. Further, the top plate of the scales of the prior art using these load cells often engage the load cells in such a manner that the top plates are damaged as the vehicle wheels are supported thereby. In addition, a plurality of load cells are often required for each portable scale (sometimes four in number) and this large number of load cells often exceeds the capacity of the readout equipment. The portable scales of the prior art are often very heavy even though they can be manually moved from one place to another.
It is therefore a principal object of this invention to provide a load cell for a portable scale which is strong, relatively light in weight, easily mounted in a scale housing, and capable of operationally housing more than one strain gauge.
A further object of this invention is to provide a portable scale utilizing a load cell that can assume the weight being imposed thereon by the top plate of the scale without resulting in deformation or other damage to the top plate of the scale.
A still further object of this invention is to provide a portable scale utilizing load cells which minimizes the number of load cells required per scale, and wherein the load scale is easily installed in the scale housing and easily serviced.
These and other objects will be apparent to those skilled in the art.